1. Field of the Invention
The present invention relates to separation of light and heavy phase liquids and, more particularly, to varying the output flow of a separation apparatus in order to separate light and heavy phase liquids so that the heavy phase liquid is separated to a predetermined concentration.
2. Discussion
In metal fabrication systems, it is often desirable to heat treat the metals to be fabricated. Heat treatment typically involves controlled heating and cooling of the metal in the solid state in order to obtain specific, desired properties. The particular type of heat treating process depends upon the desired result and characteristics of the metal. One operation performed in the heat treatment process involves rapidly cooling metal in order to fabricate hard metal. This process is referred to as quenching. Quenching involves cooling the metal at a rate sufficient to form the desired metallurgical properties while minimizing residual stresses, distortion, and the possibility of cracking.
One particular quenching operation utilizes polymer quenchants. Polymer quenchants include solutions of organic polymers and water. The organic polymers contain corrosion inhibitors, as well as other additives, to produce a concentrated solution which is further diluted into a suitable quench solution. Examples of organic polymers used in polymer quenching operations include polyalkylene glycol (PAG), sodium polyacrylate (ACR), polyvinyl pyrrolidone (PVC), and other polymers. Because various polymer quenchants possess different properties, the selection of a particular polymer depends upon the desired quenching characteristics. The quenching characteristics can further be varied by selection of polymer concentration, temperature of the polymer, and the degree of agitation. Factors considered when selecting polymer quenchants include hardenability of the metal, thickness, and surface finish of the quenched metal, as well as other properties.
Polymer quenchants provide numerous advantages. Polymer quenchants are non-flammable, thereby significantly reducing the risk of fire and eliminating the need for expensive fire extinguishing systems. Polymer quenchants also provide a safer working environment by eliminating smoke and fumes during the quenching process and by eliminating the oily environments resulting from the use of more commonly used quenching oils. Polymer quenchants also provide numerous other technical advantages, as are known to those skilled in the art.
One particular advantage of polymer quenchants is that varied concentrations of the polymer quenchant provide flexibility of the quenching process to achieve a particular, desired result. Recently, some quenchant installations have included forms of quenchant management systems for varying the concentration of quenchant in the quench tank in order to vary the properties of the quenching operation. The quenchant management system receives fluid from the quench tank and recovers heavy and light phase components from the liquid received from the quench tank. The heavy phase component comprises the polymer quenchant in predetermined concentrations, and the light phase component comprises substantially water with a typical low level polymer quenchant concentration.
Existing quenchant management systems recover the polymer quenchants through thermal separation or through reverse osmosis. In thermal separation, the polymer quenchant is heated within a tank to cause separation into a heavy phase and a light phase which are then individually removed. While thermal separation may be relatively inexpensive, thermal separation does not provide the desired accuracy in the concentrations of the heavy and light phase components, requiring additional apparatus and operations to verify the concentrations of the recovered polymer. Reverse osmosis, on the other hand, is more accurate in the recovery of heavy and light phase components than thermal separation, but is much more expensive to manufacture and maintain.
Therefore, it is an object of the present invention to provide a quenchant management system which allows for accurate recovery of polymer quenchant in predetermined concentrations.